"Diatomaceous Earth is an all-natural dewormer for chickens." - Statement found on popular Facebook Chicken group page posted on February 3, 2016.
For more information, check out this research on the Effect of Diatomaceous Earth on parasite load, egg production, and egg quality of free-range organic laying hens.
* It's important to note that while the birds in the study did have a smaller load of worms, they still in fact had worms. ~ Andy Schneider (The Chicken Whisperer)